A trip cock device is usually mounted on a rapid transit car and connected to the brake pipe, so that, when the trip cock is actuated by a trip arm fixed to the track, the brake pipe is vented to atmosphere, via the trip cock, to effect, in a well-known manner, an emergency brake application. The trip arm is usually placed in an area that is prohibited to the train on which the trip cock is mounted. Presently-used trip cocks, once actuated, automatically reset themselves, so that the engineer, who is required to report such incidents each time they occur, may ignore the incident and neglect to report it.